A 71-year-old man was referred to our hospital for further examination of abnormal sputum cytology. No abnormal nodular shadows were detected in chest X-ray and chest CT. The location of the tumor was clearly identified as a defect of autofluorescence by autofluorescence bronchoscopy at the bifurcation between the left B1+2 and B3 bronchi, whereas it was quite difficult by conventional bronchoscopy. Transbronchial biopsy revealed squamous cell carcinoma. Further examinations yielded the diagnosis of early-stage lung cancer. Photodynamic therapy was performed and complete response was confirmed. This case indicates the efficacy of autofluorescence bronchoscopy for detecting early-stage lung cancer.